Air conditioner

ABSTRACT

Disclosed is an air conditioner. The air conditioner includes: at least one indoor unit; an outdoor unit communicating with the indoor unit and having at least one compressor and one outdoor heat exchanger; a fluid path opening/closing valve for opening or closing a fluid path through which a refrigerant can flow to the outdoor heat exchanger; and a control unit for controlling the compressor and the fluid path opening/closing valve to perform appropriate compression and condensation of the refrigerant according to the load amount of the indoor unit. Accordingly, as the air conditioner comprises the fluid path opening/closing valve and the branch fluid path opening/closing valve which are capable of opening or closing fluid paths and a control unit for controlling the valves, a high pressure of a cycle is appropriately maintained even during small-load operation and therefore reliability in operation can be increased.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an air conditioner, and particularly,to an air conditioner capable of appropriately maintaining a highpressure of a cycle during small-load operation.

2. Description of the Background Art

An air conditioner is for adjusting temperature, humidity, air currentand cleanliness of air in order to create a pleasant indoor environment.According to the unit construction, there are an integral type airconditioner in which an indoor unit and an outdoor unit are receivedinside one single case and a separated type air conditioner in which acompressor and a condenser as an indoor unit are separated from anevaporator as an outdoor unit.

An air conditioner for both heating and cooling, which is part of theair conditioner, is provided with a fluid path switch valve and switchesa fluid path of a refrigerant to thereby selectively perform its coolingor heating function. Recently, the use of the so-called multi-type airconditioner having a plurality of indoor units capable of cooling orheating according to indoor spaces has been increasing.

In the multi-type air conditioner, a plurality of outdoor units having aplurality of compressors and a plurality of outdoor heat exchangers areconnected to each other in parallel.

FIG. 1 is a schematic view of a conventional multi-type air conditioner.With reference to FIG. 1, a conventional multi-type air conditionerincludes: a plurality of indoor units 10 having indoor heat exchangers11 and indoor expansion devices 13, and a plurality of outdoor units 20having outdoor heat exchangers 41 and compressors 23. With theconstruction of FIG. 1, the outdoor units 20 supply the compressedrefrigerant to each of the indoor units 10 via a pipe 30 and cool spaceswhere the indoor units 10 are installed.

Meanwhile, the multi-air conditioner performs condensation by using theoutdoor heat exchangers 41 of all the outdoor units 20 even when someindoor units 10 perform cooling operations. As a result, a condenserwhich is large in comparison to the area and air flow of the heatexchangers corresponding to the indoor unit 10 load is used.Accordingly, a phenomenon that the system high pressure decreasesoccurs.

When the phenomenon that the system high pressure decreases occurs, adifference between a high pressure and a low pressure is reduced andtherefore the refrigerant cannot be smoothly supplied to the indoorunits 10 when the pipe 30 for connecting the indoor units 10 and theoutdoor units 20 to each other is long or when a difference in altitudebetween the indoor units 10 and the outdoor units 20 is great. Inaddition, since the lower pressure decreases simultaneously when thehigh pressure of the system decreases, the pipe of the indoor units 10can be frozen. In particular, such a phenomenon frequently occurs at lowoutdoor temperature.

Accordingly, the refrigerant cannot be smoothly supplied to the indoorunits 10 and the pipe of the indoor units 10 is frozen. Thus, cooling orheating is impossible.

BRIEF DESCRIPTION OF THE INVENTION

Therefore, an object of the present invention is to provide an airconditioner capable of appropriately maintaining a high pressure of acycle during small-load operation.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is provided an air conditioner comprising: at least one indoorunit; an outdoor unit communicating with the indoor unit and having atleast one compressor and one outdoor heat exchanger; a fluid pathopening/closing valve for opening or closing a fluid path through whicha refrigerant can flow to the outdoor heat exchanger; and a control unitfor controlling the compressor and the fluid path opening/closing valveto perform appropriate compression and condensation of the refrigerantaccording to the load amount of the indoor unit.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a schematic view of a conventional multi-type air conditioner;

FIG. 2 is a construction view of an air conditioner in accordance with afirst embodiment of the present invention;

FIG. 3 is a control block diagram of FIG. 2;

FIG. 4 is a construction view of an air conditioner in accordance with asecond embodiment of the present invention;

FIG. 5 is a construction view showing an important part of an airconditioner in accordance with a third embodiment of the presentinvention;

FIG. 6 is a control block diagram of FIGS. 4 and 5;

FIG. 7 is a construction view of an air conditioner in accordance with afourth embodiment of the present invention; and

FIG. 8 is a control block diagram of FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an air conditioner in accordance with one embodiment of thepresent invention will be described in detail with reference to theaccompanying drawings. FIG. 2 is a construction view of an airconditioner in accordance with a first embodiment of the presentinvention, and FIG. 3 is a control block diagram of FIG. 2. Forreference, a construction showing the same operation and effect as theaforementioned and illustrated construction will be given the samereference numerals, and a description therefor will be omitted.

With reference to FIGS. 2 and 3, an air conditioner in accordance withthe first embodiment includes an indoor unit 10, an outdoor unit 20, afluid path opening/closing valve 55 and a control unit 51.

Each of the indoor units 10 is disposed indoors, and includes an indoorheat exchanger 11, a cooling fan (not illustrated) disposed to promoteheat exchange of the indoor heat exchanger 11 and an indoor expansiondevice 13 disposed at one side of the indoor heat exchanger 11 so as toexpand a refrigerant.

The outdoor unit 20 includes compressors 23 for compressing arefrigerant and a pair of outdoor heat exchangers 41 and 41′ connectedwith the compressors 23.

The compressors 23 are connected to each other via a flow pipe 25through which oil can flow, and each of the compressors 23 has an oilseparator 27 and a check valve 29 at its discharge side.

The downstream side of the check valves 29 along the direction of therefrigerant flow join together at a confluence junction. A four-wayvalve 31 is installed on the downstream side of the confluence junctionso as to switch a fluid path of the refrigerant.

Each port of the four-way valve 31 communicates with each one end ofconnection pipes 33 connected with the indoor heat exchangers 41 and41′, an accumulator 35 and the indoor unit 10, respectively.

Check valves 43 and outdoor expansion devices 45 are provided on thedownstream side of the outdoor heat exchangers 41 and 41′, respectively,along the direction of the refrigerant flow.

The fluid path opening/closing valve 55 is disposed on the upstream sideof the outdoor heat exchanger 41′ along the direction of the refrigerantflow. The fluid path opening/closing valve 55 blocks the fluid path ofthe refrigerant during small-load operation, and comprises an electricvalve such as solenoid in order to allow the control by an electricsignal.

The control unit 51 is implemented in the form of MICOM having a controlprogram therein and is electrically connected with the compressors 23and the fluid path opening/closing valve 55. The control unit 51calculates the load during small-load operation by which some indoorunits 10 are operated, and appropriately controls compression andcondensation on the basis of the calculated load.

Hereinafter, the operation of an air conditioner illustrated in FIGS. 2and 3 will be described.

When some indoor units 10 are operated, the control unit 51 calculatesthe cooling or heating load. Of course, the control unit 51 cancalculate the cooling or heating load when all the indoor units 10 areoperated.

According to the calculated cooling or heating load, the control unit 51control the compressors 23 such that some compressors 23 are operated orthe compressors 23 are operated at low frequencies.

In addition, the control unit 51 controls the fluid path opening/closingvalve 55 such that the compressed refrigerant flows or does not flow tothe outdoor heat exchanger 41′. The compressors 23 and the fluid pathopening/closing 55 can be simultaneously or sequentially controlled asoccasion demands.

Accordingly, the air conditioner having the construction of FIGS. 2 and3 can perform condensation corresponding only to the amount of theindoor unit 10 load when some indoor units 10 perform cooling or heatingoperation, so that a decrease of the system high pressure does notoccur.

FIG. 4 is a construction view of an air conditioner in accordance with asecond embodiment, FIG. 5 is a construction view illustrating animportant part of an air conditioner in accordance with a thirdembodiment, and FIG. 6 is a control block diagram of FIGS. 4 and 5.

With reference to FIG. 4, an air conditioner in accordance with a secondembodiment includes an indoor unit 10, an outdoor unit 20, a fluid pathopening/closing valve 55, a branch fluid path opening/closing valve 49and a control unit 51.

Since the indoor unit 10 has the same construction and operation as theindoor unit 10 described in the first embodiment, a description thereforwill be omitted.

The outdoor unit 20 includes compressors 23 for compressing arefrigerant and outdoor heat exchangers 41 and 41′ connected with thecompressors 23.

Since the compressor 23 has the same construction and operation as thecompressor 23 described in the first embodiment, a description thereforwill be omitted.

In order that the optimum amount of refrigerant can flow, the outdoorheat exchangers 41 and 41′ include a plurality of heat exchange units 42separated from each other; headers 47 having branch fluid paths throughwhich the refrigerant branches off and is supplied to each of the heatexchange units 42; and distributors 57, respectively.

The branch fluid path includes a plurality of upstream branch fluidpaths 48 for connecting the header 47 with the heat exchange unit 42,and a plurality of downstream branch fluid paths 58 for connecting theheat exchange unit 42 with the distributor 57.

The fluid path opening/closing valve 55 is installed on the upstreamside of the header 47 of the outdoor heat exchanger 41′, and opens orcloses the corresponding fluid path.

The branch fluid path opening/closing valve 49 is installed on theupstream branch path 48 of the outer heat exchanger 41, and opens orcloses the upstream branch fluid path 48 along the direction of therefrigerant flow.

FIG. 5 illustrates an air conditioner according to a third embodiment inwhich a location where the branch fluid path opening/closing valve 49 isinstalled is changed from the upstream branch fluid path 48 of FIG. 4 tothe downstream branch fluid path 58. With reference to FIG. 5, thebranch fluid path opening/closing valve 49 opens or closes thedownstream branch fluid path 58. Of course, the branch fluid pathopening/closing valves 49 can be installed at both the upstream branchfluid path 48 and the downstream branch fluid paths 58.

With reference to FIG. 6, the control 51 is implemented as MICOM havinga control program therein, and is electrically connected with thecompressors 23, the fluid path opening/closing valve 55 and the branchfluid path opening/closing valve 59. The control unit 51 calculates theload during small-load operation by which some indoor units 10 areoperated. On the basis of the calculated load, the control unit 51appropriately controls compression and condensation of the refrigerant.

Hereinafter, the operation of the air conditioner illustrated in FIGS. 4to 6 will be described.

When some indoor units 10 perform cooling operations, the control unit51 calculates the cooing or heating load. Of course, if all the indoorunits 10 perform cooling operations, the control unit 51 can calculatethe cooling or heating load.

According to the calculated cooling or heating load, the control unit 51controls the compressors 23 such that some compressors 23 are operatedor the compressors 23 are operated at low frequencies.

In addition, the control unit 51 controls the fluid path opening/closingvalve 55 such that the compressed refrigerant flows or does not flow tothe outdoor heat exchanger 41′.

In addition, the control unit 51 controls the branch fluid pathopening/closing valve 49 such that the compressed refrigerant flows ordoes not flow to the outdoor heat exchanger 41.

The compressors 23, the fluid path opening/closing valve 55 and thebranch fluid path opening/closing valve 49 can be simultaneously orsequentially controlled as occasion demands.

Accordingly, the air conditioner having the construction of FIGS. 4 to 6can perform condensation corresponding to the amount of the indoor unit10 load when some indoor units 10 perform cooling or heating operation,so that the decrease of the system high pressure does not occur.

FIG. 7 is a construction view of an air conditioner in accordance with afourth embodiment of the present invention and FIG. 8 is a control blockdiagram of FIG. 7. With reference to FIGS. 7 and 8, the air conditionerin accordance with the fourth embodiment includes an indoor unit 10, anoutdoor unit 20, a fluid path opening/closing valve 55, a branch fluidpath opening/closing valve 59 and a control unit 51.

Since the indoor unit 10 has the same construction and operation as theindoor unit described in the first embodiment, a description thereforwill be omitted.

The outdoor unit 20 includes a main outdoor unit 21 a and a sub-outdoorunit 21 b connected and installed in parallel.

The main outdoor unit 21 a and the sub-outdoor unit 21 b include aplurality of compressors 23, a plurality of outdoor heat exchangers 41and 41′ and accumulators 35 and four-way valves 31, respectively.

Oil separators 27 and check valves 29 are installed at discharge sidesof the compressors 23 of the main outdoor unit 21 a and the sub-outdoorunit 21 b, respectively.

A pressure equalizing pipe 15 is provided between the main outdoor unit21 a and the sub-outdoor unit 21 b so as to allow the upstream side ofthe outdoor heat exchangers 41 and 41′ of the main outdoor unit 21 a andthe upstream side of the outdoor heat exchangers 41 and 41′ of thesub-outdoor unit 21 b to communicate with each other along the directionof the refrigerant flow.

The fluid path opening/closing valves 55 are installed on the upstreamside of the outdoor heat exchanger 41 and 41′ of the main outdoor unit21 a and on the upstream of the outdoor heat exchangers 41 and 41′ ofthe sub-outdoor unit 21 b, respectively, so as to open or close thecorresponding fluid path along the direction of the refrigerant flow.

The branch fluid path opening/closing valve 59 is installed at thedownstream branch fluid path 58 of the outdoor heat exchanger 41 of themain outdoor unit 21 a so as to open or close the corresponding branchfluid path 58.

With reference to FIG. 8, the control unit 51 is implemented in the formof MICOM having a control program therein, and is electrically connectedwith the compressors 23, the fluid path opening/closing valve 55 and thebranch fluid path opening/closing valve 59.

The control unit 51 calculates the load during small-load operation bywhich some indoor units 10 are operated and appropriately controlscompression and condensation on the basis of the calculated load.

Hereinafter, the operation of the air conditioner illustrated in FIGS. 7and 8 will be described.

When some indoor units 10 perform cooling operations, the control unit51 calculates the cooling or heating load. Of course, when all theindoor units 10 perform cooling operations, the control unit 51 cancalculate the cooling or heating load.

According to the calculated cooling or heating load, the control unit 51controls the compressors 23 such that some compressors 23 are operatedor the compressors 23 are operated at low frequencies.

In addition, the control unit 51 controls the fluid path opening/closingvalve 55 such that the compressed refrigerant can flow or cannot flow tothe outdoor heat exchanger 41 and 41′ of the main outdoor unit 21 a andto the outdoor heat exchangers 41 and 41′ of the sub-outdoor unit 21 b.

In addition, the control unit 51 controls the branch fluid pathopening/closing path 49 such that the compressed refrigerant can flow orcannot flow to the outdoor heat exchanger 41 of the main outdoor unit 21a.

The compressor 23, the fluid path opening/closing valve 55 and thebranch fluid path opening/closing valve 59 can be simultaneously orsequentially controlled as occasion demands.

Accordingly, the air conditioner having the construction of FIGS. 4 to 6can perform condensation corresponding to the amount of the indoor unit10 load when some indoor units 10 perform cooling or heating operation,so that the decrease of the system high pressure does not occur.

The air conditioner in accordance with one embodiment of the presentinvention of which description has been made so far includes the fluidpath opening/closing valve and the branch fluid path opening/closingvalve which are capable of opening or closing fluid paths and a controlunit for controlling the valves. Accordingly, even during the small-loadoperation, a high pressure of a cycle is appropriately maintained tothusly increase reliability in operation.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

1. An air conditioner comprising: at least one indoor unit; an outdoorunit communicating with the indoor unit and having at least onecompressor and one outdoor heat exchanger; a fluid path opening/closingvalve for opening or closing a fluid path through which a refrigerantcan flow to the outdoor heat exchanger; and a control unit forcontrolling the compressor and the fluid path opening/closing valve toperform appropriate compression and condensation of the refrigerantaccording to the load amount of the indoor unit.
 2. The air conditionerof claim 1, wherein the fluid path opening/closing valve is disposed onthe upstream side of the outdoor heat exchanger along the direction ofthe refrigerant flow.
 3. The air conditioner of claim 2, wherein thefluid path opening/closing valve is an electric valve.
 4. The airconditioner of claim 1, wherein the control unit, according to the loadamount obtained by calculating the load when some indoor units areoperated, controls the compressors such that some compressors areoperated or the compressors are operated at low frequencies, and opensor closes the fluid path opening/closing valve.
 5. The air conditionerof claim 1, wherein the outdoor heat exchanger comprises: a plurality ofheat exchange units in which the refrigerant branches off and flows, andperforming heat exchange; a header having branch fluid paths throughwhich the refrigerant can branch off and be supplied to the heatexchange units; and a distributor connected with the heat exchangeunits.
 6. The air conditioner of claim 5, further comprising: a branchfluid path opening/closing valve for opening or closing the branch fluidpath.
 7. The air conditioner of claim 6, wherein the branch fluid pathcomprises: an upstream branch fluid path for connecting the header withthe heat exchange units; and a downstream fluid path for connecting theheat exchange units and the distributor, wherein the branch fluid pathopening/closing valve is installed at either the upstream branch fluidpath or the downstream branch fluid path.
 8. The air conditioner ofclaim 6, wherein the branch fluid path comprises: an upstream branchfluid path through which the header is connected with the heat exchangeunits; and a downstream fluid path through which the heat exchange unitsare connected with the distributor, wherein the branch fluid pathopening/closing valves are installed at both the upstream branch fluidpath and the downstream branch fluid path.
 9. The air conditioner ofclaim 6, wherein the control unit, according to the load amount obtainedby calculating the load when some indoor units are operated, controlsthe compressors such that some compressors are operated or thecompressors are operated at low frequencies, and opens or closes thefluid path opening/closing valve and the branch fluid pathopening/closing valve.
 10. The air conditioner of claim 6, wherein theoutdoor unit comprises a main outdoor unit and a sub-outdoor unitconnected and installed in parallel.
 11. The air conditioner of claim10, further comprising: a pressure equalizing pipe for allowing theupstream side of the outdoor heat exchanger of the main outdoor unit andthe upstream side of the outdoor heat exchanger of the sub-outdoor unitto communicate with each other.
 12. The air conditioner of claim 10,wherein the fluid path opening/closing valves are installed on theupstream side of the outdoor heat exchanger of the main outdoor unit andon the upstream side of the outdoor heat exchanger of the sub-outdoorunit.
 13. The air conditioner of claim 10, wherein the branch fluid pathopening/closing valve is installed at the downstream branch fluid pathof the outdoor heat exchanger of the main outdoor unit.
 14. The airconditioner of claim 10, wherein the control unit, according to the loadamount obtained by calculating the load when some indoor units areoperated, controls the compressors such that some compressors of themain outdoor unit and the sub-outdoor unit are operated or thecompressors are operated at low frequencies, and opens or closes thefluid path opening/closing valve and the branch fluid pathopening/closing valve.
 15. An air conditioner comprising: at least oneindoor unit; an outdoor unit communicating with the indoor unit andhaving at least one compressor and a plurality of heat exchange units inwhich the refrigerant branches off and flows and performing heatexchange and a header having branch fluid paths through which therefrigerant can branch off and be supplied to the heat exchange unitsand a distributor connected with the heat exchange units; a fluid pathopening/closing valve are installed on the upstream side of the headerfor opening or closing a fluid path through which a refrigerant can flowto the header; and a control unit for controlling the compressor and thefluid path opening/closing valve to perform appropriate compression andcondensation of the refrigerant according to the load amount of theindoor unit.
 16. The air conditioner of claim 15, further comprising: abranch fluid path opening/closing valve for opening or closing thebranch fluid path.
 17. The air conditioner of claim 16, wherein thebranch fluid path comprises: an upstream branch fluid path forconnecting the header with the heat exchange units; and a downstreamfluid path for connecting the heat exchange units and the distributor,wherein the branch fluid path opening/closing valve is installed ateither the upstream branch fluid path or the downstream branch fluidpath.
 18. The air conditioner of claim 16, wherein the branch fluid pathcomprises: an upstream branch fluid path through which the header isconnected with the heat exchange units; and a downstream fluid paththrough which the heat exchange units are connected with thedistributor, wherein the branch fluid path opening/closing valves areinstalled at both the upstream branch fluid path and the downstreambranch fluid path.
 19. The air conditioner of claim 16, wherein thecontrol unit, according to the load amount obtained by calculating theload when some indoor units are operated, controls the compressors suchthat some compressors are operated or the compressors are operated atlow frequencies, and opens or closes the fluid path opening/closingvalve and the branch fluid path opening/closing valve.
 20. The airconditioner of claim 16, wherein the outdoor unit comprises a mainoutdoor unit and a sub-outdoor unit connected and installed in parallel.